A driving battery is disposed at the lower side of a floor portion of an electric vehicle. Structuring a battery case that accommodates the driving battery in a two-layer structure of an upper plate and a lower plate formed of a resin material (a fiber-reinforced resin composite material) has been known since heretofore (for example, see Japanese Patent Application Laid-Open (JP-A) Nos. 2012-94476 and 2011-146341).
A vehicle battery container that has also been known since heretofore has a two-layer structure formed of an inner wall and an outer wall. A connection piece is formed by inflection so as to protrude from the inner wall toward the outer wall at an acute angle, and the outer wall and inner wall are connected by this connection piece (for example, see JP-A No. 2012-89377).